1. Field of the Invention
This invention relates to devices for metering chemicals, and more particularly to an apparatus for controlled dissolution and metering the flow of a water treatment chemical into a water supply.
2. Description of the Prior Art
The problem of mineral deposits which build up on plumbing, appliances, and the like, which handle or utilize water in their operation is well known, and those problems are particularly severe in those regions having hard water. These well known mineral deposit have been known to cause equipment malfunctions and will, in general, decrease the operating efficiency and useful life of equipment.
By way of example, the problem of mineral deposition is particularly troublesome in air cooling devices which operate on an evaporation principle such as the device commonly called an "evaporative cooler".
Briefly, an evaporative cooler includes a centrifugal blower for drawing air into a housing through wettable excelsior pads so that evaporation will chill the air which is ultimately delivered to a point of use by the blower. The cooler housing usually includes a water reservoir or sump in the bottom thereof, and a pump for directing the water from the sump into a plumbing network which distributes the water to the excelsior pads to keep them wet, with the water passing through the pads and back into the sump. Thus, the evaporative cooler is seen to be a water recirculating device in which accelerated evaporation takes place, and the mineral deposit buildup in the pump, plumbing, pads, and all the other components of such a device is severe.
Many methods and devices have been tried in attempts to ease the mineral deposition problems in evaporative coolers and other equipment having such problems. However, no device or method known to me has functioned well enough to achieve commercial success.
One method that was tried without appreciable success was that of depositing controlled amounts of a chemical commonly called sodium glassy phosphates into the water supply. However, the nature of that chemical makes it difficult to meter controlled amounts thereof into a water supply, and that problem has heretofore not been overcome to the best of my knowledge.
Sodium glassy phosphates are versatile chemicals with desirable properties such as water softening, sequestering, peptizing and suspension of finely divided solids, scale and corrosion prevention. The glassy phosphates belong to a group of linear chain polymers commonly called "condensed phosphates" or "polyphosphates" and are sometimes referred to as "sodium hexametaphosphate".
The glassy phosphates can be dissolved in water to make concentrated solutions, but such solutions are viscous. When the glassy phosphates are in particulate form, such as powder or grandular, it can be dissolved in water provided that the water is well agitated. If the rate of agitation is insufficient, the glassy phosphate will settle to the bottom and form a gelatinous mass which is very slow to dissolve.
The above stated properties of glassy phosphates make is a very desirable chemical for water treatment purposes, however, the properties of that chemical make it difficult to use.
Therefore, a need exists for a new and useful apparatus for metering water treatment chemicals in general and sodium glassy phosphates in particular, into a water supply for treatment thereof.